Question

Please answer the following questions/fill in the data tables based on the following experiment.

EXPERIMENTAL PROCEDURE:

Place sodium hydroxide (2.500 g) in a 100 mL Erlenmeyer flask and add water (25.0 mL) and ethanol (20.0 mL). Add a magnetic stirrer bar and stir until all the NaOH has dissolved. To a second reaction vessel, add benzaldehyde (2.650 g, 0.025 mol) and acetone (0.725 g, 0.0125 mol). Add approximately half of the aldehyde-ketone solution to the sodium hydroxide solution, and stir for 10 minutes with a watch glass covering the top of the flask. After this time, add the remainder and stir for a further 10 minutes. Filter off the product using a Buchner funnel and wash the product with water until the washings no longer appear to be basic (test using pH paper). The best way to do this is to remove the vacuum tube from the filter flask, fill the Buchner funnel with water, carefully stir the product with a glass rod and re-apply the vacuum. Each time the funnel is filled with water, add some litmus paper to the solution to test the pH. When all traces of NaOH have been removed via water washing, dry the product and record the mass and melting point of the crude product. Then calculate the percent yield. Recrystallize the product from the minimum amount of hot ethanol, recording the mass, melting point and percent yield of the pure product.

Finish the data table here. You need to show your work in order to get full credits.

1. Mass of benzaldehyde used ____2.650 g____

2. Moles of benzaldehyde ______________

3. Moles of dibenzalacetone expected (theoretical yield) _______________

4. Mass of dibenzalacetone expected _______________

5. Mass of dibenzalacetone obtained _____2.221g ___

6. % yield of dibenzalacetone _______________

7. Observed melting point of dibenzalacetone __ 105.5 ∞C ___

8. Literature melting point of dibenzalacetone _______________

9) Draw the structures of the cis and trans isomers of the compound that you prepared. Which one is the major product? Explain why?

Answer 1

# Chemical Reaction CHO Naot of 2. + H₂O Moles benzal of Mass of the benzaldehyde used= [2.650 g dehyde = molar mass of benzaldehy de- 106 g/mol. mass (a) 10.0250 mol moles of benzaldehyde molar mass (Homos) 2.650 g 10 6 Ilmos 0.0250 mol. 3 0.0125 mol stoitio metrically 2 mol. Moles of dibenzalacetone expected benzaldehyde produces Imol dibenzalacetone. (2 x 0. 0250) So 0.0250 mol benzaldehy de produces, 0.0125 mol di benzal acetone. 0.0250 mol 0.0 125 mol 2 2.9258 Mass of dibenzed acetone expected molar mass of dibenzal acetone = 234 g/mol

moles f of dibenzal acetone produced a 0.0 125 mei dibenzal acetone = 0.0 125 mol x 234 g mass mol 2.925 g Mass of dibenzal acetone obtained - 2.2219 ③ % yield of dibenzal acetone 75: 93% Actual yield 7 % yield- x100 % Theoretical field 2.2218 x100 %. 2.925 g 75.93.1 meeting point & observed of dibenzal acetone - 105.5°C Literature melting point of dibenzal acetone oring 110°C H trams- trans. H H cis-trans cis-cis There are three cis-trans isomer, obtained for dibenzal acetone.

Among them trans trans isomer is more stable (order of stability trans trans cis-trans 7 cis cis. Reason these The given order of stability among isomers is due to sterie repulsion. Inease of trans- trans isomer such interaction is than others stence it has highest stability less